I have told the story before about the EPA researcher who had a meter for measuring air quality that he was using to take readings at a busy intersection along 14th St, NW in Washington, DC at evening rush hour in the 1980s. He recorded his readings, but forgot to shut if off when he went home. He got home and set the meter near the door in his kitchen, turned on the gas oven to fix dinner and went upstairs to change clothes. When he got back down to the kitchen, the meter was going crazy with higher readings for nitrous oxide and other pollutants than it had measured at the rush hour intersection along a major commuter artery with bumper to bumper traffic for blocks. It scared the hell out of him when he considered what he had been inhaling right in his kitchen.
You also have to face the fact that when many of us were growing up, the stove was on for three meals a day unless no one was there for lunch. There was no microwave oven and no fast food, shocking as that may seem to you youngsters reading this. Granted, houses were not as tight as newer ones are, but almost none had vented range hoods. I also remember that many evenings, especially in the winter, when mom was fixing dinner, the normally blue flames would have orange flashes in them. I asked her what that was and she said it was impurities in the gas due to high demand. I don't know if that was right, but it was something that did not happen at other times.
Does anyone remember entering an apartment building and immediately detecting the smell of gas stoves? If you inspected the stoves, you would find a little deposit of carbon glowing orange along the edges above the pilot lights. Maybe it is different now with more of the ranges changing over to pilotless ignition, but it was an unpleasant odor to me and could not have been healthy to breathe over a long period of time.